Composite tubing



United States Patent [72] Inventor Albert E. Chl'OW 837,512 12/1906Seeley 138/138 Chagrin Falls, Ohio 3,211,823 lO/1965 Brown et al.....138/122X [211 App]. No. 697,670 3,277,231 10/1966 Downey et al.. 174/47[22] Filed Jan. 15,1968 3,300,571 1/1967 Downey et al.. 174/47Continuation-impart of Ser. No. 510,202, 3,367,370 2/1968 Sherlockl74/47UX Nov. 29, 1965, Patent No. 3,445,583 FOREIGN PATENTS [45]Patented Dec-1,1970 191,686 10/1956 Austria 138/138 [73] Asslgnee SamuelMoore and Company Mantua, Ohio Primary Exammer-Laverne D. Geiger acorporation f Ohio Assistant Examiner- Henry K. Artis Attomey-Teare,Teare, & Sammon [54] COMPOSITE TUBING 13 Claims, 8 Drawing Figs.

174/47 ABSTRACT: A composite tubing product for transmission of 1- flFl55/00 fluid under high pressure, including an inner polymeric core[50] Field of Search 138/138, tube and an outer polymeric protectivesheath surrounding 122, 141, 103, 125, 118, 121, 130, 129, 140, 144, thecore tube. An electrical discharge element is disposed 149, 154, 150;174/47 between the inner core tube and the outer sheath and extends in aspirally wound relation with respect to the axis of the core [56]References Cited tube, and a particle penetration-resistant,envelopelike sleeve UNITED STATES PATENTS 646,887 4/1900 Stoweetal.

is disposed around the discharge element in engaged relation with theinner core tube.

Patented Dec. 1, 1970 mW m mH VC N E T R E B L A ATTORNEYS COMPOSITETUBING This application is a continuation-in-part of the copending U.S.Pat. application Ser. No. 510,202 to Albert E. Chrow, filed Nov. 29,1965 now US. Pat. No. 3,445,583.

BACKGROUND OF THE INVENTION The present invention relates in general tocomposite tubing for use in connection with mechanical devices fortransmission of fluid under high pressure, and more particularly totubing having an electrical discharge means, such as a metallic groundwire, incorporated therewith for use with fluid spray equipment or thelike.

Composite tubing or hoses are used to transport a liquid such as paintor the like from a pulsating source of power such as a hydraulic pump toa spray nozzle, such as a spray gun or the like, where the liquid issprayed upon an object. Because a considerable amount of staticelectrical charge is produced along the core of the hose, it isdesirable to incorporate an electrically conductive ground wire in thestructure of the hose so as to drain off such static charge to preventsudden sparking at the spray nozzle. Such sparking occurs when too muchelectric static charge is built up in the device and a worker uses thespray nozzle too close to a grounded conductor, such as a steel beam. Inorder to transmit the liquid under sufficient pressure to produce anadequate spray, the hose is generally of a high pressure constructioninvolving a relatively strong, though flexible inner tube or core, afibrous reinforcement layer to protect against bursting, and an outerprotective coating, usually polymeric, to protect the tubing fromabrasion, moisture, temperature variations and corrosion. It isdesirable that such hose radially expands under the pressure pulsationsin order to act as an accumulator which attenuates the pulses so as tominimize the pulsating at the nozzle and thereby produce a more smoothand uniform painting spray.

. The practice in the past has been to incorporate this grounding wireas one of the braids of the reinforcement. In another form, the wire wasmolded into the core along one side thereof in a zigzag fashion. Thedifficulty with the prior art type of arrangement is that such wiresoften broke under pressure and thereby lost their effectiveness as agrounding device for a static charge. One attempt which had been made tosolve the problem was to a make the hose less susceptible to expansion.Such approach was helpful in decreasing breakage of the wire but tendedto make the hose less effective as it severely decreased in accumulatoraction and thus caused undesirable pulsation at the nozzle of the paintspray gun.

For an example of the prior art type devices, reference may be had tothe U.S. Pat. No. 3,042,737 to Robert E. Brumback et al.

SUMMARY OF THE INVENTION A composite tubing product comprising an innerpolymeric core tube for transmitting fluid under pressure and an outerprotective sheath surrounding the core tube. An electrical dischargemeans is disposed between the core tube and the protective sheath and isspirally wound with predetermined axial spaced pitch distances withrespect to the axis of the core tube, and a particle-resistant orrupture-resistant envelopelike sleeve is disposed in encompassingrelation around the discharge means in engaged relation with the innercore tube.

7 By this arrangement, there is provided an improved composite tubingproduct, including means for discharging or grounding an electricalcharge produced upon use of the tubing which minimizes breakage orrupture of the electrical components upon pulsation or expansion of thetubing, which minimizes abrasion of the electrical components andprovides a lubrication for the components upon pulsation or expansion ofthe tubing, which has good accumulator and fatigue failurecharacteristics, and which provides a simplified and efficientarrangement for maintaining the electrical conductivity and electricaldischarge and/or grounding characteristics of the assembly.

BRIEF DESCRIPTION OF THE DRAWINGS Referring now to the drawings, FIG. 1is a fragmentary partially cut away and partially cross-sectionedelevation view of a section of paint hose according to the presentinvention;

FIG. 2 is an enlarged fragmentary cross section of a composite painthose taken along the lines 2-2 in FIG. 1;

FIG. 3 is a fragmentary elevation view of a section of the inner coretube illustrating the grounding element or twisted wires, disposedspirally of the core tube in accordance with the present invention;

FIG. 4 is a vector diagram illustrating the forces exerted on agrounding element according to the prior art where the wire turns areclosely spaced;

FIG. 5 is a vector diagram illustrating the forces applied to thegrounding element disposed according to the present invention;

FIG. 6 is an enlarged fragmentary cross section taken along the lines6-6 of FIG. 1, illustrating a cross section of the grounding elementwhen assembled with the composite tubing and prior to rupture thereof;

FIG. 7 is an enlarged fragmentary cross-sectional sectional viewillustrating a partial disintegration of the grounding element of FIG. 6during operation; and

FIG. 8 is a cross section illustrating the adjacent of the protectivetape of FIGS. 6 and 7 after fragments break through the binder tapeduring operation.

Referring again to the drawings and more particularly to FIGS. 1 and 2thereof, there is illustrated a composite tubing T made in accordancewith the present invention and having an inner tube or core 10, agrounding element 12, such as a plurality of twisted wires, disposedhelically of the inner tube 10 and covered by a binder tape 14 which inturn is covered by a protective tape 16. The binder tape 14 andprotective tape 16 follow the helical convoluted path of the groundingelement 12, as best illustrated in the right-hand portion of FIG. I. Areinforcement sheath 18 of fibrous material may be disposedcircumferentially of the tubing to reinforce the tubing forhigh-pressure operations and an outer protective sheath 20 may bedisposed circumferentially of the reinforcement sheath to protect thecomposite product from corrosion, abrasion, and/or adverse temperatures.

One feature of the invention is that the grounding element 12 may bewound helically of the inner tube 10 and in a manner so that the spacingbetween adjacent convolutions is much greater than ordinarily hasheretofore been the case in the prior type of tubing. As shown in FIG.3, it is desirable to wind the grounding element 12 so that the distanceY between corresponding axially spaced points on the convolutions, suchas between crests 22 and 24, is at least four times the outer diameterof the inner tube 10. It is even preferred that the aforesaid pitchdistance be 16 times the diameter of the tube. For example, where thediameter of the inner tube 10 is onequarter inch, it is preferred thatthe pitch distance be 4 inches. It has been found that by greatlyincreasing the pitch distance, an extremely flexible hose constructionmay be utilized so as to permit substantial swelling or diametricalexpansion of the hose so as to provide the desired accumulator actionwhich minimizes the pulsation at the nozzle without subjecting theground wire 10 to abnormal stresses and strains. It is preferred thatthe composite product expand as much as 11 percent of its diameter. Therupture of the grounding element 12 is caused by radially directedcomponents of force. As shown in the vector diagram of FIG. 4, wherein ahelical winding of the closely packed arrangement is made, the radialcomponent 0 to R is substantial. In FIG. 4, as 45 lay is shown. In FIG.5, it is seen that where the angle of the lay is extremely acute, theradially outwardly directed component of force 0 to R is very slight ascompared to its corresponding force shown in FIG. 4. It is to beunderstood that the angle of lay or the pitch distance maybe more orless than that described but that the use of some pronounced elongation,as compared to the conventional tight winding, may be of greatassistance in achieving the composite structure of the presentinvention.

While nylon is a preferred material for the construction of the innertube and of the reinforcement sheath, it is to be understood that anymaterials which are strong enough to resist premature breaking, yetwhich are flexible enough to permit the expansion to achieve theaccumulator effect may be used.

Preferred results are obtained wherein the grounding element iscomprised of a plurality of twisted wires. It is believed that aplurality of wires such as shown in FIGS. 6 to 8 is useful in achievinga disintegration of the grounding wire which, when used in cooperationwith the other elements, retains electrical continuity as hereinafterdescribed. Preferred results have been obtained by the use of a 8 2X34AWG tinned copper, flattened braid, or the 8X2X34 AWG, bare oxygen-freecopper.

The aforesaid axial disposition of the convolutions is utilized tominimize the occurence of breakage over normal usage. Equally important,it is designed to decrease the extent of breakage of the groundingelement when it does occur. When this feature of a minimized extent ofbreakage is utilized in conjunction with the application of the bindertape 14 and the protective tape 16 of the present invention, theusefulness of the grounding element as a static energy dissipater isstill available even though a rupture has occurred in the element. Ithas been found that the electrical conductivity of the grounding elementmay be sustained by confining the particles in sufficiently closephysical proximity or contact with each other that the electricalconductivity is maintained even though a rupture has occurred and theelement is no longer the continuous solid entity which it was duringassembly.

The continuity of the electrical circuit is maintained by thedisposition of a binder tape 14 which is placed over the groundingelement 12, as shown in FIG. 1 and FIG. 2, so as to bind the elementinposition. The preferred binding tape should have good fatigueresistance and adhesive characteristics and good elongation. Preferably,the tape should be as wide as the groundingelement which is covers andpreferably, slightly wider. A preferred form of binder tapethree-eighths inch wide by 4 mil thickness vinyl, such as type 471 soldby Minnesota Mining and Manufacturing Company. Other types of bindingtapes may be utilized such as Mylar adhesive, semiplasticized vinyls, orvarious adhesive bearing thermoplastic or thermosetting resins as wellas the use of impregnants such as latexes, plastisols, organisols,liquid urethanes, or epoxies. While it is not necessary to do so, thebinder tape may completely cover the tube rather than merely followingthe path of the element, if desired. The tape must be capable ofexpansion so as not to be ruptured due to the action of the swelling ordiametrical expansion of the tube due to the pulsation of the liquidtherethrough and must be a sufficiently good binder to hold thefragmented particles 30 formed when a portion of the element ruptures,as shown in FIG. 7.

When the grounding element disintegrates after rupture, there is apossibility that one of the pieces or particles of the grounding elementwill break through the binder tape and cut the superimposed fibrousreinforcement sheet. Accordingly, a protective tape 16 may be providedto overlie the binder tape 14, as shown in FIG. 1. Thus, as shown inFIG. 8, should a rupture occur, the protective tape 16 shields thefibrous reinforcement 18 from the displaced grounding wire particles 32,thereby preventing abrasion, cutting or other damage to thereinforcement sheath and also confines the particles so as to maintainthe electrical continuity of the grounding element. It is preferred thatthe protective tape follow the path of the convoluted wire. The tapecould also be wound circumferentially of the binder tape and inner coreso as to form a continuous encompassing sheath though such completeencasement is not necessary.

Now, in accordance with the invention, there is provided an inner orsupportlike tape 40 which coacts with the protective tape 16 to form aconduit or confining envelope around and for the wire grounding element12. As shown, the support tape 40 is disposed in engaged relation on theinner tube 10 and in a pattern corresponding to the lay of the element12 and hence, the binder and protective tapes 14 and 16. Preferably, thesupport tape 40 is coextensive in width (FIG. 1) with that of theprotective tape 16 and hence, slightly less than that of the binder tape14. In this form, the outer confronting marginal edges of the supporttape 40 and the protective tape 16 may be secured together, as at 42, toprovide the envelopelike structure. This securement may be achieved, inthe embodiment shown, by means of a heat seal along the opposed marginaledges or by means ofa suitable adhesive of the type known in the art. Bythis arrangement, the inner support tape 40 coacts with protective tape16 to provide an envelopelike enclosure around the grounding element tpto prevent any be breakthrough of the fragmented particles, as at 30,when a portion of the element ruptures, as discussed in connection withFIGS. 6 to 8. Accordingly, this construction affords an improvedpredetermined confinement of the material of the grounding elements soas to maintain the continuity of the electrical system to which thecomposite tubing may be applied. In addition, it will be seen that thesupport tape 40 provides an effective lubricated working surface uponwhich the grounding element 12 is mounted. Accordingly, the exposedconfronting surface of the support tape 40 affords a working surface toenable free sliding movement of the grounding ele ment l2 thereon whichmay result form expansion and/or flexure of the tubing, thereby toprevent breaks in the grounding element.

As best seen in FIG. 2, the respective superposed tapes 40, 14 and 12provide a laminated construction, but with the grounding element 12disposed in a snug fitting, sandwiched relation between tapes 40 and 14.Accordingly, the binder tape 14 being substantially free of securementto the protective tape 16 or the support tape 40 may move with respectthereto to accommodate expansion of the tube, as aforesaid. However, thebinder tape 14 may have some limited securement adjacent its terminal ormarginal edges, as at 44, due to the presence of the heat seal oradhesive material at the seam area 42.

In the invention, it is preferred that the protective tape 16 and thesupport tape 40 be made from an abrasion and particlepenetration-resistant material. As an example, a preferred form of tapematerial is Mylar which is a polyethylene terephthalate polyesteravailable from Dupont.

The outer reinforcement sheath of fibrous material may be of aconventional braid type or it may be of a series of coplanar layers. Itis preferred that the braid material and construction be such as topermit sufficient diametrical expansion to act as an accumulator for theliquid, such as paint and the like, passing through the hose so that thepulsation at the nozzle of the spray gun is minimized. A preferredmaterial for the reinforcement layer is nylon. However, other materials,such as dacron may be used. Dacron is the trade name of a polyesterfiber sold by Dupont.

The thickness of the grounding element will depend on the degree ofconductivity required. For example, where the hose is one-fourth inch indiameter, then it has been found desirable to use an element having amaximum initial resistance of 0.6 ohms for 25 linear feet of hose.

The outer protective sheath 20 may be of a polymeric material whichprovides flexibility, and good temperature and abrasion resistance. Apreferred material for the sheath is polyurethane. The thickness may bein the rangeof 0.020 to 0.025 inch on a Aa-inch diameter inner core.

The foregoing composite structure for a paint hose and the like providesa hose which is capable of extreme radial outward expansion so astoprovide an accumulator effect for paint and the like passing through thehose and thereby minimize pulsation at the nozzle while at the same timeproviding a grounding element to drain off static electricity to preventsparking at the nozzle should the nozzle be placed in too closeproximity to another conductor whereby the rupture-free life of thegrounding element is greatly increased and whereby the electricalcontinuity and operation of the grounding element is maintained eventhough a rupture does occur and the fatigue life of the hose isincreased.

Whereas the prior art structure, wherein the grounding element formed apart of the braid, lost electrical continuity at approximately 1,000cycles, the structure of the present invention has operated from 50,000cycles to in excess of 100,000 cycles without such loss.

The terms and expressions which have been used, are used as terms ofdescription and not of limitation, and there is no intention in the useof such terms and expressions of excluding any equivalents of any of thefeatures shown or described, or portions thereof, but it is recognizedthat various modifications are possible within the scope of theinvention claimed.

lclaim:

l. A composite tubing product for fluid pressure transmissioncomprising:

an innerpolymeric core tube for transmitting fluid under pressure;

a reinforcement sheath of fibrous material disposed around said coretube; an electrical conductive element disposed in spirally wouldrelation with respect to the axis of said core tube and disposed betweensaid core tube and said reinforcement sheath;

an inner support tape disposed in engaged relation between said coretube and said conductive element;

an outer protective tape secured to said support tape on opposed sidesof and in confining covering relation throughout the length of saidconductive element to form an envelopelike sleeve around said conductiveelement to maintain electrical continuity upon expansion or flexure ofsaid tubing; and

said conductive element being disposed in movable relation within saidsleeve to accommodate expansion of said tub- 2. A composite tubingproduct in accordance with claim 1, wherein:

said inner and outer tapes are made from a polymeric material; saidinner and outer tapes being secured together adjacent their marginaledges; and

said conductor element being disposed for sliding movement on said innertape.

3. A composite tubing product in accordance with claim 1, including anintermediate binder tape disposed in covering relation between saidconductor element and said outer protective tape. v

4. A composite tubing product in accordance with claim 1, wherein saidinner and outer tapes are substantially coextensive in width.

5. A composite tubing in accordance with claim 4, wherein saidintermediate tape is of a lessor width as compared to said inner andouter tapes, and has a width sufficient to cover said conductor element.

6. A composite tubing product in accordance with claim 1, wherein saidinner and outer tapes are made from a polymeric material.

7. A composite tubing product in accordance with claim 1, wherein thepitch distance between adjacent convolutions of said conductor elementis greater than the diameter of said inner core tube.

8. A composite product in accordance with claim l,'including an outerpolymeric protective sheath disposed around said reinforcement sheath.

9. A composite tubing product in accordance with claim 1, wherein saidsleeve comprises a polymeric laminatelike structure, and said conductorelement disposed in sandwiched relation within said structure.

10. A tubing product in accordance with claim 3, wherein said bindertape is substantially free of securement with respect to said outer tapeand said inner tape to enable movement with respect thereto toaccommodate expansion of said t n l L A tubing product in accordancewith claim 1, wherein:

said inner and outer tapes are made of a polymeric material;

and

said inner tape has greater abrasion resistantcharacteristics ascompared to said outer tape.

12. A composite tubing product in accordance with claim 1, wherein saidinner tape is made of a polyethylene terephthalate polyester.

13. A composite tubing product having good burst strength, fatigue,diametrical expansion and electrical continuity characteristics for usein transmitting pressurized pulsating fluid comprising:

an inner polymeric core tube having an axially extending bore for thetransmission of said fluid;

a continuous electrical conductive element disposed in helicallyconvoluted relation around said core tube and substantially coextensivein length with said tubing;

a reinforcement sheath of fibrous material disposed in circumferentiallyengaged relation around said core tube;

an abrasion resistant inner support tape disposed in secured relation tosaid core tube and in engaged relation to said conductive element;

an outer protective tape secured to said support tape on opposed sidesof said conductive element throughout the length thereof to form anenvelopelike sleeve around said conductive element; and

an intermediate binder tape disposed in engaged relation with saidsupport tape and in engaged confining covering relation throughout thelength of said conductive element between said conductive element andsaid outer protective tape to maintain the electrical continuity of saidconductive element.

